1. Field
Example embodiments relate to an organic light-emitting display device and a method of manufacturing the same. More particularly, example embodiments relate to an organic light-emitting display device having improved light coupling efficiency and a method of manufacturing the organic light-emitting display device.
2. Description of the Related Art
Light efficiency of organic light-emitting display devices is classified into internal efficiency and external efficiency. The internal efficiency relies on photoelectric conversion efficiency of an organic light-emitting material, and the external efficiency, i.e., light coupling efficiency, depends on each refractive index of each layer of the organic light-emitting display device.
The organic light-emitting display devices can be classified into a top emission type and a bottom emission type according to a light emitting direction. In the top emission type organic light-emitting display device, an image is displayed in a direction directed away from a substrate on which an organic light-emitting diode is formed. The top emission type organic light-emitting display device may have a greater aperture ratio than that of the bottom emission type organic light-emitting display device, i.e., a device in which an image is displayed toward a substrate on which an organic light-emitting diode is formed, and thus may have higher light emission efficiency.
In the top emission type organic light-emitting display device, a transparent cathode is formed in an uppermost portion of the organic light-emitting display device. However, a material for forming the cathode may be limited due to a low work function of the cathode, i.e., a basic characteristic of the cathode, thereby limiting light efficiency of the organic light-emitting display device.